This application is based upon application No. 11-359095 filed in Japan, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a driving system with elastically supporting units. More specifically, the present invention relates to the driving system for driving a driven member in a plane.
2. Description of the Related Arts
When a camera body is moved or shaken at time of photographing, an image-forming position or a position of object image, onto a photosensitive surface, is deviated or shifted out of position. In order to prevent such a deviation or shift of the image-forming position, there have been proposed various types of blur compensation mechanisms, in which a blur compensation lens provided in a lens barrel is moved suitably, on a basis of the detected direction and distance of the deviation caused by such a shaking of the camera body, so as to keep the deviation of the image-forming position onto the photosensitive surface within a certain range.
However, the conventional blur compensation mechanisms are constructed so that two blur compensation lenses are driven independently in two directions perpendicular to each other, because they are needed to be driven precisely at high speed. Thereby, the construction thereof becomes large, and it is difficult to make the mechanism compact, especially in a direction of an optical axis, i.e. in a direction perpendicular to the driving directions in which the blur compensation lenses are driven.
Accordingly, it is an object of the present invention to provide a driving system that is compact in a direction perpendicular to the driving directions in which the blur compensation lens is driven to move.
In order to achieve the above object, there is provided a driving system comprising: a driven member; and at least three supporting units for supporting the driven member and for elastically urging the driven member in directions generally perpendicular to an axis thereof, at least one of the supporting units being of a driving type including a frictionally driving unit, the frictionally driving unit being restrained from moving a direction perpendicular to a direction in which the driven member is urged and having a contact portion for contacting the driven member under pressure, the contact portion vibrating at high frequency so as to move the driven member in a direction generally perpendicular to the direction in which the driven member is urged.
In the construction, the driven member is supported on at least three supporting points, as the result of the balance of urging forces of the supporting units. The contact portion of the frictionally driving unit, which is included by at least one of the supporting units, can move or drive at least one of the supporting points by the vibration thereof so that the driven member is moved to and supported at new balanced position. That is, it is possible to move the driven member.
In the construction, the frictionally driving unit may include, for example, a piezoelectric actuator, which is of the successively driving type, more specifically, a vibration motor or so-called ultrasonic motor in which high frequent vibration makes the driven member moved. In the case, the vibration motor may be of a stationary wave type, of which the contact portion for contacting the driven member vibrates in elliptic shape in a stationary manner. Also, it may be of a progressive wave type, which drives the driven member by means of the surface vibration in elliptic shape caused by the progressive wave. Depending on the contact of the frictionally driving unit with the driven member under pressure, it is possible to move the driven member by the small distance so as to control the movement of the driven member precisely with high resolution. Thus, after driving the driven member, it is possible to support the driven member without play.
In the construction, since the supporting units support the driven member from directions perpendicular to the axis of the driven member the supporting units can be disposed only in the space which extends in driving directions, except for in the space which extends in a direction perpendicular to driving direction.
Accordingly, the driving system can be made compact in the direction perpendicular to the axis of the driven member.
As an embodiment, all of the supporting units may be of the driving type.
In this embodiment, even if the force perpendicular to urging direction of respective supporting units is applied, sliding is caused between the driven member and the supporting units. Thus, the supporting unit cannot be forced excessively and can drive the driven member with small force at the stabile condition.
As another embodiment, at least two of the supporting units may be of the driving type.
In this embodiment, in the case that the driving type of supporting units are disposed not parallel to each other, it is possible to move the driven member in two directions. Meanwhile, in the case that the driving type of the supporting units are disposed parallel to each other, it is possible to rotate the driven member.
As still another embodiment, the at least one of the supporting units being of the driving type may urge the driven member toward the axis of the driven member elastically so as to support the driven member.
In this embodiment, urging toward the axis of the driven unit cannot cause redundant moment in the driven member. Thereby, the contact portion of the driving type of supporting units contact the driven member equally so as to drive the driven member at the stable condition.
As still another embodiment, there may be provided two pairs of the supporting units beside the driven member at right angles in a plane perpendicular to the axis of the driven unit, and at least one of each of the two pairs thereof may be of the driving type.
In this embodiment, each pair of the supporting units is disposed perpendicular to each other and at least one of the pairs is of the driving type. Thus, it is possible to drive the driven member in two directions without rotating it.
As still another embodiment, there may be provided three of the supporting units beside the driven member at generally trisected positions in a plane perpendicular to the axis of the driven member so as to urge the driven member toward the axis of the driven member, and at least two of the supporting units being of the driving type.
In this embodiment, at least two of the driving type of the supporting units, disposed about 120 degree apart, can drives the driven member in two directions by the resultant force thereof. Moreover, it is possible to rotate the driven member.
As still another embodiment, the driving system may further comprise a holding unit for holding the driven member, the holding unit including: an urging member for urging the driven member in a direction parallel to the axis of the driven member; and a contacting member for contacting the driven member so as to prevent the driven member from moving in a direction of urging the driven member. In this embodiment, the holding unit can keep the position of the driven member constant in a direction parallel to the axis of the driven member.
In this embodiment, the urging member may include a contact face, contacting the driven member under the pressure and urged by the supporting, the contact face tilting to (or being inclined against) both the axis of the driven member and a plane perpendicular to the axis of the driven member so as to generate a component of urging force in a direction parallel to the axis of the driven member. By means of the component of urging forces in the direction parallel the axis of the driven member, it is possible to support the driven member elastically and to make the construction of the driving system compact.
Above mentioned constructions of the driving system is suitable to a blur compensating apparatus to drive an image blur compensation lens in a direction perpendicular to an optical axis thereof.
Further, in order to achieve the above object, there is provided a driving system comprising: a driven member; a guide for guiding the driven member movably in a plane; a first elastic member for contacting the driven member from a first direction in the plane; a second elastic member for contacting the driven member from a second direction in the plane; and a third elastic member for contacting the driven member from a third direction in the plane, the third elastic member including a contact portion for contacting the driven member, the contact portion being restrained from moving in a direction perpendicular to the third direction in the plane and vibrating in the direction perpendicular to the third direction in the plane.
As an embodiment, the second elastic member may include a second contact portion for contacting the driven member, the second contact portion being restrained from moving in a direction perpendicular to the second direction in the plane and vibrating in the direction perpendicular to the second direction in the plane.
In this embodiment, the second direction may be perpendicular to the third direction.
Moreover, the driving system may further comprise a forth elastic member for contacting the driven member from a forth direction in the plane, the first direction opposing the second direction, and the third direction opposing the forth direction.
As another embodiment, the driven member may have a circular contact face for contacting the first elastic member, the second elastic member, and the third elastic member at generally trisected positions.